


Killers second chance

by Nestle25



Series: You'll be okay [3]
Category: Undertale (Video Game)
Genre: Chara is a lil shit, Dream the uncaring, Extreme sarcasm, Killer doesn't try, Killer hates everything, Nightmare is a mess, he's done with everything
Language: English
Status: Completed
Published: 2021-01-28
Updated: 2021-02-25
Packaged: 2021-03-14 10:15:36
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence, Major Character Death
Chapters: 5
Words: 9,721
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29044467
Author URL: https://archiveofourown.org/users/Nestle25/pseuds/Nestle25
Summary: He was done, tired of caring about anything anymore. Chara was in charge and he was powerless against them. But with them being gone he has no one now. So why is this octopus skeleton looking monster trying to kidnap him? He isn't worth anyone's time anyway.
Series: You'll be okay [3]
Series URL: https://archiveofourown.org/series/2027971
Comments: 342
Kudos: 33





	1. Charas killing spree

**Author's Note:**

> Chara is just a monster right now and Sans is in it for the long haul.

“Good job Sans! I can’t believe you actually killed him..” Chara said as they walked beside Sans, he was quiet and looked around in solemn. Dust covered his entire body and all he could think about was every single monster's face once he had appeared to take the final blow. The pair was now in Hotland, looking around he already knew everyone had evacuated. 

“Hey Sans why are you so quiet?”

“I just want to get this over with.” He said sternly as they saw two royal guards, Chara took out their knife and smiled at Sans before running up to them. They smiled at the two guards before slicing them into pieces, their screams pierced through Sans ears before he walked up to them, he stabbed the last remaining guard repeatedly until they were dust. Chara got up and giggled excitedly and looked at Sans.

“See I told you this was fun! Are you having fun?” Sans shrugged his shoulders and brushed off some of the dust, though it stuck to his fingers as a reminder of what he’s done. They continued on their murderous path and grabbed some items on the way to find more monsters. He wasn't surprised to see Chara all giggly about killing innocent monsters but it still scared him nonetheless.

“Man we should really do this again sometime, it's waaayyy more fun when you’re helping. It was way better than just killing you like everyone else.” He was getting irritated but continued to ignore Chara as the smell of dust flowed through the air. Wondering why he even agreed to this he slipped out his small piece of cloth from Papyrus's scarf. Chara looked at his directions and tried to take a peek at what he had, their hand creeped up to Sans as they tried to grab it from him. He practically hissed and held onto it for dear life.

“What do you have there, I wanna see it!”

“Back off you little shit, this is mine.” He growled as his hand immediately clamped on the cloth. Chara hummed and whistled as if he wasn’t already annoyed with them, he knew they would be the worst on a road trip. He hated this already and their antics were only making it worse, he knew that they knew what they were doing.

“Oh! Sans look over there!” A Vulkin was running around, he seemed frightened and bewildered as dust covered the floor around him. He turned around to look at the other two completely covered in dust. Chara laughed excitedly and took out her knife once again and began to stab the screaming Vulkin, once again the noise hurt his ears and he stabbed the monster finally allowing him to die.

“Y’know Sans I really never took you as the killing type.”

“Well I never took you as the teammate type either.” Sans retorted.

“Are you in a bad mood again Sans?”

Sans said nothing, he already knew what Chara would say after, they smiled and started to pat his skull.

“I know you don’t want me to reset so you can kill your brother again do you?” Chara threatened, Sans shook his head and stared at the ground. Sans had known the little psychopath would do it if he didn’t follow their every command. Chara burst out laughing and dragged him off to find another monster in the area, he never liked it when Chara laughed only because that's when he knew someone would die soon. 

“It was weird how Undyne was so angry with you for killing Papyrus. I know she would have never let Papyrus be in the royal guard and look now Alphys is on her own too! It's gonna be so easy and so much fun!” They squealed in excitement as they continued to talk. Sans found himself zoning out as the voices were ringing in his head, his ears were buzzing and he felt as if he would go deaf.

Sans had never thought of hurting Chara, though he knew what would happen if he did. Or did he? Now that he had a high lv maybe things would be different this time, he would have enough power to overtake them. His confidence was nothing compared to Chara's bloodlust so he tried to get the idea out of his head, he could never distract Chara long enough to get a hit in anyways. 

“Ugghh It's been an hour and we've found nothing, I’m bored!” Chara complained as they had reached the mtt resort. 

“How about you go take a rest and I’ll be on the lookout.” Sans offered, Chara smiled and took the offer. They went into one of the rooms and Chara went to take a nap. Sans sat on a chair nearby, as time passed he crept to the sleeping child and snapped his fingers in front of them. No answer. 

Was this his chance, could he finally be rid of this demon and bring back his family? He summoned a bone and raised it high above their head. He started to sweat and focused on the head. He was right there so why couldn’t he do it? He couldn’t..

He grumbled to himself and realized how hard his hands were shaking, he doubted that he could get a perfect hit because of it. He let the bone fall and deteriorate on the floor. He sat back on the chair and held his hands on his forehead, he tried to fight the tears that were pouring down his sockets. Chara listened quietly and smiled hearing him finally sob, they did it. They broke him.

After another hour of ‘sleeping’ Chara got up and then looked around the whole resort, they found a couple of monsters in the area and were quick to dispose of them. The tear marks were still visible on the scarred skeleton and Chara was quick to point it out.

“What happened there?” They asked trying to see if he would say anything.

“Got something in my eye..”

“What was it?”

“..Dust.” Chara nodded as they killed a few other monsters that came by.

“I love this feeling, the quicker the better too huh Sans?” He nodded his head just trying not to talk.

“Sans! You’re working with the human?” They both turned around to see Mettaton as angry as the robot could express. He shot at the pair but they were quick to dodge, Chara ran up and tried to stab Mettaton but was kicked to the wall. For a moment Sans panicked not knowing what to do, but he shook it off and shot a blaster at Metton who shot at the balster. They both disappeared as Metton gave a desperate look to Sans.

“Please Sans stop this, I know this isn’t you. Alphys, Undyne… Papyrus, they wouldn’t want this” Sans felt a ping of regret before Chara stabbed Mettaton in the neck multiple times, he looked up to the skeleton and smiled.

“I hope you liked my last live-action.” His eyes turned pure black and the robot fell, his body started to blow smoke. Sans felt something he hadn’t felt in a while. Regret. He could never take back what he did, so what did he have to lose?

“Hahaha Sans you should have seen the way they looked at me before he- Sans…?” He hovered over the human with a knife in his hands. Chara chuckled nervously and tried to look more intimidating.

“If you kill me I’ll reset over and over, I’ll make you kill your brother for eternity!” Chara screamed as Sans stayed still, he enjoyed the way Chara was getting nervous and squirmed around. 

“D-Don’t do anything you’ll regret Sans…” He smiled at them

“I already regret everything.” He stabbed Chara in the chest, they looked down before blood came out of their mouth. They coughed furiously and they held their throat, Sans ripped the knife out and sat down watching them die. 

“I’ll c-c-come back..”

“I’ll be waiting.” Sans stated as Chara held their hand out to Sans before falling dead on the floor. He waited for what felt like hours before getting up and leaving the bloody scene.

There was never a reset…  
He was free! He looked at his soul and almost thought he’d dust right then and there. His soul was red, with a circle and another circle surrounding it, looking almost like a donut. He felt himself shake looking at it, he quickly unsummoned his soul and continued on. His eyes felt funny but he ignored it, not wanting to see what is going on with him.

He ended up killing all the monsters he could find, he finally reached Asgore's throne room. He slowly walked in and looked around to see Asgore looking down at him, his face looked in horror as black tears traced down the skeleton's face. He reached a hand out to Sans but quickly pulled back, he looked away from the murderous crazed skeleton.

“Sans.. I trusted you…” Asgore sadly said and all Sans could do was look down in silence. 

“I’m sorry Sans but you know what I must do now.” He took out his weapon and shook his head, Sans felt himself cry out as he took out the knife. The only person who gave him such a high position and trusted him, and he was going to kill him.

He ran and tried to slice Asgore's side but his armor shielded him from it, he pulled back and fell to the ground to avoid Asgore's attack. He tried to jump on Asgore but failed, he was thrown into the wall by the goat monster. Sans felt his bones crack at the impact, he fell on his back and struggled to get up, Asgore hovered over Sans and went to stab him. Sans threw himself out of the way and was able to grab Asgore’s cape. He climbed to the top and slit his throat, Asgore fell to the floor and held his neck, Sans stood in front of him. He regret weighed over him like a ton of bricks as tears once again threatened to fall.

“I'm sorry..” He whispered at Asgore, he reached a hand out to Sans who grabbed his hand. Asgore squeezed his hand and smiled before he turned to dust leaving Sans all alone. 

Sans sat down and cried out loudly, he hit the floor repeatedly until his voice shriveled up. He was so tired, he laid down and tried to take a nap. He woke up and looked around, he figured he would just go back home, the walk back was excruciatingly quiet. The coldness of the world surrounded him like a blanket, though it did the exact opposite of a blanket. He tried to not think as he reached his house. He sat on his bed and curled in on himself. The voices wouldn't leave him alone. He could never live with what he has done, he was all alone now. He killed everyone he knew and loved for what? Chara wasn't coming back, but so were they. Everything was gone and it was all his fault.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

An unknown monster teleported into his world, badly wounded. He struggled to stand upright and leaned against a tree. Arrows were pointed out of his arms and legs, he staggered his walking as he tried to approach the seemingly empty house. He fell down halfway, he was more annoyed than anything. He then proceeded to rip out the arrows from his arms and legs. He screamed in pain as he tried to get up once again. The pain was unbearable, especially knowing who put you in the pain in the first place. He hoped no one was in the house, he didn't want to start trouble again.

But he was so pissed he didn’t have words to describe it, he threw the door down with his tentacle and walked in. He went to pass out on the couch and the two unknowing slept in the same house undisturbed.


	2. No means no

**Notes for the Chapter:**

> Sans and Nightmare can't get along.

When Nightmare woke up his wounds were healed, he was thankful for that as he looked around, he saw a picture of a bone which made him chuckle a bit as he wandered. He went upstairs and looked in the first room, it was neat and tidy. He went to the second room but felt a strong feeling of negativity, he opened the door to see a skeleton curled up in a blanket. He slowly approached and shook the bundle with one of his tentacles, Sans turned around and screamed.

He shot out a knife and ran to Nightmare before he evaded the attack, he went behind Sans and tried to calm him down. 

“Hey it’s okay I’m not gonna hurt you!” He screamed as Sans went to stab him again. It was odd because Sans had never seen him before but the monster looked like him. He stopped attacking and threw the knife, there was no point anymore. He lowered his head and closed his eyes.

“You should kill me while you have the chance,” Sans said looking down, Nightmare looked at him worriedly and shook his head. “I don’t want to do that.” Sans looked up in surprise and confusion.

“Why not?” 

“I don't even know you so why would I kill you?”

“Not knowing them is even better.” Nightmare hummed in response not knowing what to say, the skeleton looked lonely and tired. 

“You don’t look happy to be here..” He commented, Sans nodded his head and sat on his bed. 

“I mean once you kill everyone you know and love you aren't really gonna be the happiest guy on the planet.” He said sarcastically, Nightmare gave a look of sympathy and almost felt the same way. He didn’t want to go back to the castle all alone and this guy looks so bad here.

“What happened?”

“Did you not hear what I just said about the whole killing my loved ones? You’re a terrible listener..”

“I just want to help, It doesn't seem like you want to be here.” Sans shrugged, having nothing to say to the monster.

“My name is Nightmare... It's nice to meet you.” He introduced, Sans snarled and flipped him off.

“Well, Nightmare you can leave thanks for stopping by.” He said turning away from him, he was definitely annoyed but he would rather have some company.

“You don’t have to stay here, I can take you somewhere better.” Nightmare offered to the uninterested skeleton. Sans scoffed and flipped him off once again. This time Nightmare wasn’t taking no for an answer and proceeded to grab Sans with his tentacle and teleported him away. Sans screamed and tried to stab Nightmares tentacles over and over.

“Hey what the fuck! I don’t want to go with you, take me back now!” Sans demanded as Nightmare set him on the couch in the living room. 

“Sorry but I don’t feel like you should stay there.”

“Who the fuck are you to say I can’t do what I want!” Sans argued, Nightmare shrugged and sat next to him.

“I felt your energy and it was pure negativity and your tears are pure hate, I just wanted to help..” Sans almost forgot about the whole crying thing until he felt his face and sure enough the tears were still there.

“I don’t cry,” Sans stated as he turned away from him.

“It's alright to cry, we all have our reasons,” Nightmare said back. 

“Take me back and I won’t kill you,” Sans said as Nightmare sighed, he asked why he wanted to go back anyway.

“I don’t need to give you a reason, take me back now.” He said angrily as Nightmare relented. They teleported back to Sans’s world and Sans looked at his door that was busted in.

“Oh are you kidding me?!” Nightmare instantly offered to fix it but Sans waved him off.

“You’ve already done enough damage so leave before anything else happens,” Sans said coldly. Nightmare apologized again and left, leaving Sans on his own once again.

Nightmare went back to his castle where the negativity and loneliness surrounded him, he sat on the couch and turned on the TV. He felt himself cry seeing his brother on the TV. 

“Dream how do you feel about the negativity in the multiverse?” A news lady asked Dream as he grabbed a microphone.

“I am feeling positive, this monster will not hurt anyone and I promise as the guardian of positivity I will make you all happy. Nightmare if you're listening I will make sure you never hurt an innocent person again.” The new lady laughed as the microphone went to Ink.

“Haha Dream and I are the best team, we will do anything we can for the people of the multiverse and that is not just a promise but a fact!”

He hated him, Dream hated him… His own brother…

Nightmare screamed and threw the remote at the TV, he was even madder since this was the third TV in the last two weeks, he had never felt so anguished in his life. All he wanted to do was be like Dream, everyone loved him and here he was getting the short end of the stick as usual. 

Those villagers deserved to be punished and he didn’t even fully know what was going on himself until he woke up like this. Now he was lonely, back then he always had Dream and now he has no one. 

Sans was back in his room and curled up on himself once again. Who the fuck was that guy? What was his problem and why did he just take him like that? Fucking creep…

He tried to get comfy but now that he was alone he could only hear the voices in his head asking why he killed them, they were haunting him. He grits his teeth and slammed his pillow to the mattress. Seriously what did he even want? Why was he so willing to help him when he didn't even need it, he was fine! He felt fine... For now at least. Knowing the tears never left no matter how hard he wiped them only proved this was Chara's doing. The tears hardened at this point and refused to get off of Sans's face. His soul was still showing and he wondered why that guy didn't just kill him right then and there. Whatever, it wasn't like he would be seeing him again anyway.

A few weeks had passed and Nightmare was growing more lonely by the second. He went to visit an Outertale world as it was very beautiful in his eyes, he enjoyed just coming there to look around and gaze at the stars. He sat down on a pile of grass and looked to the sky, the stars were vibrant with color. He could stay there forever until his brother came of course. 

“Nightmare what are you doing?” He whipped around as the strong emotions of positivity flowed through the area. Dream stood there with an arrow aimed at his head, Nightmare slowly stood up and looked disappointedly at Dream. He wasn't even doing anything! Now he was going to get attacked for no reason once again.

“Sometimes I like to just sit out here, what can I not do that anymore too?” Dream said nothing and looked away, he shot the arrow which went through his arm. Nightmare screeched in pain and teleported away where he sensed strong negative emotions. 

He looked around and realized this was the same world he had been to, he wondered if Sans was still around. He went to the door and saw there was tape covered all over it to keep it from falling. He could already tell there was bound to be a lot of snow in the house which wasn’t healthy for him.   
Sans was making some eggs as he heard the door creak, he instantly brought out his knife and peeked to the door. He noticed the black tentacle slithering its way in. He realized he was strong and probably could not overpower the octopus-like monster, he ignored it and went back to the eggs. 

“Hello, Sans are you in here?”

“In the kitchen.” Nightmare made his way in to meet Sans who flipped the eggs in the pan, though Sans didn’t want to he went to grab an extra plate. Nightmare stood there awkwardly not sure what to say.

“Sorry, I’m back here… I was low on negativity..”

“Negativity? What is that supposed to mean?” Before Nightmare could say, Sans pointed to the table and motioned for him to sit, he did so and thought of an easy way to explain it.

“I am the king of negativity and I must make sure there is enough negativity in the world or the balance won’t be well... Balanced?” He tried to explain to Sans who only nodded in response. 

He put the two plates down and gave Nightmare a fork.

“Oh sorry, I don’t need to eat you should though.” Sans stared daggers at him until he slowly ate.

“Don’t apologize all the time, you have no reason to.” He said as he took a bite, he coughed and made a sour face.

“Ugh this is disgusting I thought I added enough spices.” He threw his away and asked Nightmare if his was bad, he shook his head and continued to eat and thanked Sans. 

“So wait, you're a king? Where are your people? Do you have servants or something?”

“Not exactly… Everyone in the multiverse is my supposed subject and I don’t have servants… I don’t have anyone.” He said blankly, staring at his now empty plate. Sans grabbed the plates and went to wash them as well as the pan.

“Well do you feel recharged now?” Sans asked Nightmare to which he nodded.

“How does the arrow feel?” Nightmare looked down and realized the arrow was still in his arm, he breathed in as he yanked it out. 

“It feels fine.” He answered nonchalantly, Sans smiled and tried to cover his mouth. Nightmare tipped his head in curiosity as Sans bursts out laughing.

“The way you said it oh man, ah that was good.” Seeing Sans smile made Nightmare smile as well, he laughed at himself too. 

“Hey, can I throw an offer on the table?”

“Lemme guess. Me, you, your house, I stay?” Nightmare slowly nodded hoping he'd say yes.

“No.”

“Why not?”

“I have my reason octo-fuck, you’re lucky I was nice to you.” Sans snarled at Nightmare who sank in his chair a bit.

“S-sorry I just, you’re all alone and I can’t understand why you want to be here. I think you’re the only person I have had an actual conversation with who isn’t my brother..” Nightmare sadly admitted, Sans turned around confused.

“You have a brother?” Nightmare nodded and got up from his chair. He thanked Sans for being kind to him and went to leave. As he approached the door he felt heat radiating from it. Odd, it was snowing outside.

“Hey Sans….” Nightmare took a few steps back hearing an unfamiliar voice at the other end of the door, Sans ran up to Nightmare and took out his knife.

“Grillby? Is that you?” Sans asked as he took a step forward to the door, Nightmare took a step back wanting to avoid Sans getting more upset.

“You took away all my customers Sans….” The wooden door now became ash as the fire monster stepped into the house. Grillby fired at the skeleton who was too stunned to even make a move, Chara said they killed him already…

A tentacle got in front of Sans and Nightmare screamed as the tentacle was burned, another shot out and hit the fire monster's clothes which sent him back outside. Sans took a moment to regain his focus as he ran outside, he went to stab Grillby but was shot at. Nightmare grabbed Grillby by the waist and threw him into a tree. 

“You never paid your tab, Sans…” The fire monster whispered as the tree caught fire, his body began to grow with the tree as it burned. Grillby was now a huge flame that sent chills down Sans’s spine as Grillby threw trees at him, Sans tried to run but was hit in the leg. He fell down and tried to move but felt a crunch from his leg, he withered around and screamed as Grillby lit the tree on fire at the end of it. Slowly but surely the fire was making its way to Sans as he panicked and tried to wiggle his way out. Nightmare looked desperately and used his tentacles to throw the tree off of him, he ran to Sans and grabbed him before teleporting away. He was passed out and not responding, he had no choice in what happened now. Grillby screamed and the fire continued to spread through the trees making him ginormous in size.

**Notes for the Chapter:**

> Nightmare couldn't help it he just had to. Now he's gonna have to deal with Sans who probably wants him dead for taking him again.
> 
> Thank you for reading!


	3. Aggressiveness

**Notes for the Chapter:**

> Sans is kinda rude to the person who saved his life.

Nightmare gently set Sans down on the couch and ran to grab some healing food, bandages, and whatever else he thought would help. He came back and set everything down and began to wrap Sans’s broken leg, he winced as his leg looked like a broken eggshell. There were many pieces missing and Nightmare couldn’t help but feel like it was never going to heal properly.

He let Sans sleep on the couch while he went to get something to eat, he was an okay cook but there was definitely room for improvement. He made chicken breast and put some spices on it. Waiting for the chicken to be at the right temperature he went to grab some soda, he grabbed the remote and turned on the TV. 

He went to a news channel as it was informative to him, well it used to be.. It was all drama now and people saying how dangerous he was and warning people. He hated how drastically it changed once Dream started to make more appearances to the public. He smelled something.. Burning? Oh, shoot the food.

He dashed into the kitchen and saw the chicken was charcoal, he turned the stove off and tried to scrape it out but it was stuck on the pan. Cursing himself he went to go water the pan and tried to pry out the chicken once again but was unsuccessful. Throwing the pan down and giving up he checked on Sans who was still unconscious. Lying down the couch next to the one Sans was on he decided to take a nap as well. 

“Wake up.” Nightmare grumbled and tried to open his eyes but was too tired, he instantly woke up once he received a fist to the face.

“Ow what was that for?” Nightmare complained caressing his cheek, Sans smiled for a moment before going back to his empty stare. 

“I told you to wake up and you didn’t.”

“That doesn’t mean you can just punch me!”

“I mean you're the king of negativity and I’m pretty sure getting hurt is negative so I did you a favor.”

“Doesn’t mean I can’t feel pain myself!” Nightmare screamed to Sans who just shrugged and held his hand out.

“Okay take me home,” Nightmare shot up from the couch and looked at him in shock. 

“You want to go home? After all of that? Your ‘home’ has been burnt to a crisp and you want to go back!”

“I’d rather stay there than here.” Sans tried to fully stand up and screamed in pain and clutched his left leg. Nightmare leaned over and held his back comfortingly only to be pushed away from Sans.

“You’re not leaving.”

“What do you mean I’m not leaving?”

“Look at you, You’re injured and you can barely stand. I’m not letting you leave, especially if Grillby is still there.” Sans almost looked impressed that Nightmare had a spine.

“Fuck you.”

“Okay, I get it you don’t like me, don’t need to emphasize the fact,” Nightmare said as he went to grab an ice pack.

Sans smirked, seeing Nightmare upset he wouldn’t be nice just because he ‘saved’ him, he can protect himself and he doesn’t need anyone. He could have killed Grillby easily, he was just taking his time that's all.

“I was trying to make lunch for once you woke up but I burned it..”

“What was it?”

“Chicken.”

“How do you burn the chicken, do you now know how to cook?”

“I do know how to cook but I was... Distracted.”

“Distracted? By what?”

“The news.” Sans face palmed himself and sat up on the couch.

‘Seriously you’re an old man.” Nightmare looked insulted for a moment before sinking on the couch.

“Don’t call me that.”

“Then make me stop, old man.” Nightmare sighed and continued to ignore him.

“Y’know maybe this is why you have no subjects, you're a pushover.” Sans continued, Nightmare was looking more upset at Sans’s words.

“I mean you said you have a brother? You say you’re lonely and have no one? Maybe that was your own fault he doesn’t talk to you, he got what he wanted from you and bounced-”

“Will you shut the fuck up? You have no idea what I've been through, you have no idea of my relationship with my brother so don’t you dare bring him into this conversation. You are lucky I didn’t leave you when you got clobbered with that tree, you wouldn’t have survived if I fucking left. Be fucking thankful that someone saved your ass from that fire monster.” Nightmare ranted as Sans stayed completely silent.

“You are staying here until you are fully healed and then I’ll drop you off to your demise after okay how's that?” Nightmare flopped back on the couch and took a deep breath, he never got that angry and he was surprised he lost his temper like that.

“I'm proud of you.” 

“What?”

“You actually got mad and defended yourself, good job.” Nightmare was confused and asked what he meant.

“Well you’re a complete pushover and as the king of negativity that can’t do, but you have potential. So I have decided I will teach you my ways.”

“..What?”

“Okay so once my leg is healed how about we go and spread some negativity,” Sans happily offered to which Nightmare shot down the suggestion. 

“It’s too risky, I can go outside for a nice walk and still get attacked just for being there. I cause negativity by my name being thrown around the multiverse.”

“That’s boring, you don’t even cause it yourself, you’re more like an urban legend.” Nightmare rolled his eyes at Sans.

“I don’t even know if your leg will ever heal properly, it was practically dusting once I got you out.”

“Guess we’ll have to wait and see then huh?” Nightmare stopped for a moment to think of a way to speed up the process, he knew there was something called healing gel? It was in an old type of AU that had mobs and a lot of crime, people were brutal in those kinds of worlds. He looked to Sans leg and wondered if that’s what would help him.

“Okay you stay here and I’ll go get you something that should heal that leg really quick.”

“Well okay, it’s not like I can go anywhere anyways,” Sans answered as Nightmare teleported off.

He always hated these AU’s and he never understood why Ink created places like this. The streets were pitch black other than an occasional lamp lighting the sky just a bit. He was in an alleyway and walked through the back of shops, he knew there had to be something here. He saw a bag that was filled to the brim with trash and as much as he didn’t want to he opened it up, of course, there was nothing inside but old candy wrappers. 

“Hey pal, monsters aren’t supposed to be in this part of town.” He turned around to see an old man, he was bald and assumed he was in his 60’s.

“You deaf or something, I said scram!” The old man threw a rock at Nightmare who just sighed and took it, the only person he ever fought was Dream and Ink.

“I am only looking for healing gel sir and I’ll be on my way,” He answered. The man only seemed to be getting angrier the more he looked at him. He pointed at the end of the alleyway where a beaten and scratched up door was.

“There are some people who give a small jar of it out, but it ain’t easy to get some, especially with monsters like you here.” He once again gave an icy glare at Nightmare before thinking about something.

“Hey how about I help you out, monsters are pretty pathetic but you were brave enough to actually make it this far. I’ll go in with you but you have to get two jars of that gel.” Nightmare agreed to the terms and the pair made their way to the end of the alleyway.

“Monsters usually don’t get healing gel, even if they're the ones that came up with the stuff.” He chuckled thinking about it which made Nightmare want to slap him, how could anyone love taking away someone’s hard work like that?

“Alright you stay here and I’ll go in first, if you hear two snaps that means come in, hear one then run.” Nightmare nodded as the man entered the door, he put his ear up to the door to hear multiple voices talking through the other side. He waited for about five minutes until he heard two snaps. He prepared himself as he stepped inside only to be greeted by a bear monster and a buff man.

“Can’t believe you tricked another poor monster into thinking this was a no monster zone.”

“Hey, you had a laugh so don’t be mad at me.” The bear monster smiled and waved at Nightmare who nervously waved back.

“Anyways I do need two jars of healing gel, one for me and one for my friend over there.” The old man pointed to Nightmare who shyly stood to the side.

The man went to grab two jars and looked to Nightmare.

“That's gonna 5,000.” 5,000!?!?

NIghtmare definitely did not have that kind of money on him, he looked to the old man who had the same money-hungry look on his face. 

“What you didn’t think we’d give this to you for free did you?” The monster bear asked as he stepped closer to Nightmare. He backed up and looked to the old man for help as it seemed humans were much more of a priority than monsters. All he did was shrug at him and pointed to a sign, he looked over and felt his heart drop.

“No money, no life.” What did that mean!?!?!

The bear monster grabbed his shirt to which Nightmare threw him back with the tentacles, he panicked and grabbed all the jars he could and teleported back. He practically fell to the floor from panicking. 

“Woah you okay man, looked like you’ve just seen a ghost.” Nightmare said nothing and set all of the jars down on the floor, Sans grabbed one and loved the color.

“It's like a pure gold kind of color, I like it,” Sans opened the jar and began to rub some onto his wound. The wound started to glow and Sans looked in awe as his cracks were no longer visible, it was completely healed except for grey scars that showed where it cracked.

“Sooo how was it?”

“Ugh, how was what?”

“Your mission?”

“My mission?”

“Yeah going out and getting the gel, how was the world?”

“Crappy, cold, and monsters are definitely not welcome unless they are buff bears.” Nightmare answered as he sat down to relax, Sans set his leg down and was relieved he didn’t feel any pain. He walked over to Nightmare and slapped his leg.

“Why do you like hitting things?”

“It’s in my nature, anyways we will start training tomorrow.”

“Training?”

“Yes, to make you the strongest and feared monster in the multiverse! Plus you got to live up to your name. When you hear the word Nightmare what do you think?”

“Someone having a bad dream?”

“And of what exactly?”

“I don’t know.”

Sans stood up proud and put his hand to his chest dramatically. “Soon they will dream of you! But we gotta put in the work first.”

“Alright well before we do that how about I show you your room?” Nightmare stood up and motioned for Sans to follow, they walked around the castle, and Sans was surprised at how big it was. They reached a long hallway of doors and he went to the closet one on the right. The room was set up very nicely with a TV, bed, nightstand, and a huge closet. He went to lay on the bed and thanked Nightmare for the room, he wished him a goodnight and went to bed. Nightmare left to his room and the whole time he wondered what exactly he just got himself into.

**Notes for the Chapter:**

> Nightmare rarely goes to different worlds since he prefers to stay in solitude but when he does he dreads seeing how people act there. He especially hates Mobtale since there is so much discrimination against monsters. People are also very deceitful in this particular AU as well so that leaves room for more problems. But hey, at least Sans is okay.
> 
> Thank you for reading!


	4. Training

**Notes for the Chapter:**

> Sans is ready! Nightmare is not...

“Wake up.” A glass of water was thrown on Nightmare's face as he sprang up, he whipped around to Nightmare angrily.

“What was that for!”

“Lesson one, always have your guard up.” Nightmare grumbled and held his head, this was going to be a long day…

“I’ll make breakfast just in case you decide to burn it.”

“Hey, it was one time.” Sans hummed and went to go cook, the kitchen had so many pots and pans. He went to see what was in the fridge and was astounded by how much there was in here, almost as if it was meant for a king! Oh, wait….

“I’ll make some bacon and eggs, always stay on the simple side.” As Sans was cooking Nightmare turned on the TV and watched the news.

“This just in, a mafiatale AU has been visited by none other than Nightmare who has stolen over 30 precious jars of healing gel, these are important since these are the only jars that can actually heal monsters and humans alike. We will now hear from a witness on the event that transpired.” The TV turned to the old man and Nightmare was seething, Sans had walked in as soon as he heard his name.

“That Nightmare character grabbed me and pinned me to a wall, he told me he was going to kill me if I didn’t show him where the healing gel factory was. So I did and he ended up taking all of it, those poor monsters were so devastated once they learned their wounds would never heal because of him..”

“Liar! You told me where it was and wanted me to get you a jar, you weren’t even for monsters! You hate them! Also, I only took 15, there were almost a hundred jars there!”

“I think the worst part was that I wanted to get a jar for my dying granddaughter, but now I don’t know what I’ll do now that it’s all gone.” The news reported gave a sympathetic look to the old man before she spoke.

“We are so sorry to hear about all of this happening sir, however, we have a special guest who we all know and love… Dream!” Dream walked out and had a giant jar of healing gel and Nightmare swore that if the man's jaw could fall off it would.

“We are so sorry for what that monster did to you, we hope this will help your granddaughter recover. Nightmare will pay for what he has done and I will make sure your world is safe.” 

“Whose the guy in the spandex?”

“My brother..” Sans gasped and tried to see the similarities but found none..

“Oh… now I see.” They both stopped and smelled the air, something was burning. Sans ran to the kitchen and pulled out the bacon from the over and turned off the stove. Nightmare followed in and smirked at Sans and opened his mouth.

“Don’t. Say. Anything.”

“...Do you not know how to cook?” Sans shot a glance at Nightmare before starting over.

~~~~~~~~~~

After breakfast the pair was outside in the backyard, Sans had brought a large piece of wood that towered over him and Nightmare.

“Okay so you know how to use those tentacles to push people away, but have you even stabbed them.”

“Only once and I wasn’t even fully aware of what I did until later on.” He answered truthfully, Sans patted him on the back and took out his knife. He went up to the wood and cut a piece at the top and in the middle.

“I can tell you aren’t an ‘I'm ready to kill’ kinda guy so we’ll start off easy.” He pointed to the top of the wood.

“The top is the head and neck, a good hit here can kill anyone quick and easy. The middle is their stomach or their hips, that’s only if you want them to die slow or hear their screams.”

“That sounds.. Really bad.”

“Well you're really bad so you have to know this kind of stuff, now repeat after me.” Sans stabbed the top of the wood making a clean hole in the middle of it, he turned to Nightmare and let him try. 

He used the tentacle to stab through the hole and made it wider on impact, sending the top of the wood to the floor. Sans nodded in approval and pointed at the middle, Nightmare did the same thing this time using three. The wood went flying everywhere as it was cracked and shattered to pieces. 

“Good job, that wasn’t bad.” Nightmare smiled at the praise before another piece of wood was placed in front of him, he did it again and again. Sans kept throwing wood at Nightmare and every single time he was able to get a good hit in. Soon the wood started to hit him as he was losing focus.

“C’mon it’s only been two hours! You can still do more!” A tentacle grabbed Sans’s wrist and he saw how tired Nightmare was.

“Okay break time.” They sat down on a couple of lawn chairs Nightmare pulled out for them, Sans looked at Nightmare and punched him in the shoulder.

“Not bad for your first try but you are gonna have to get more… angry.”

“Angry?”

“Yep, let your anger out on all who stand in your way. Dream won’t be as brave as he is if you actually make a scene, have you ever outwardly attacked anyone?”

“Only once but I’d rather not get into that, Dream isn’t scared of me and I don’t know how to feel about that.”

“You should be angry! You're the king of negativity for crying out loud, you need to show him you're the boss!”

“Eh.. Wait do you feel that?” There was something odd about the air, it felt more.. Heavy.

“Somethings not right,” Sans commented as they went back inside, Nightmare tried to think and grabbed Sans as they teleported off. They ended up in a place where negativity was being created, there was running and screaming in the town. They were in a flowerfell AU, Nightmare was quick to notice the number of monsters that were clutching their stomach before dusting.  
The sky was turning white and was glitching in a way Nightmare had only seen a handful of times before, Sans made no moves and just watched everyone scream and cry.

“We should kill the last remaining ones..”

“What? Sans no we need to leave immediately or we’ll end up just like them.” He went to grab Sans but he sprinted, he ran to a small monster child who looked afraid as Sans stabbed them repeatedly. 

“Killer! You just killed my baby!” A monster with one arm ran to him in anger as he smiled, he was quick to dodge the fist and sliced her waist, she screamed and fell to the floor. 

“Oh my, they did this! Mobsters, Killers!” There was an uproar as Nightmare went to retrieve Sans from his murder spree, trying to think of a way to let Nightmare want to stay.

“They’re in pain Boss we gotta take them out of their misery, look at them!” Nightmare surveyed the area to see all the horrible faces and bodies dusting. He relented and let Sans go who instantly chased after running monsters, Nightmare breathed in and stabbed a man running to him with a sword.   
Soon it became a frenzy as Nightmare and Sans stabbed and killed anyone and everything they saw, he almost smiled after hurting so many people.

There was none left now so he ran to Sans and teleported off with him as the world went white.

“Oh man, that was a rush! I am so proud of you Nightmare! I can’t believe we just killed an entire universe like that! How’s that even possible!”

“From seeing it happen multiple times my guess is that two AU’s were smashed together so one must go and that is the weakest or the smallest, there also doesn’t seem to be a lot of room for them either. That world was small so that's my theory.’

“Does it happen a lot?”

“Depends.”

“Oh…”

Nightmare stood up and saw all the dust on him and looked at Sans who had, even more, he was practically doused in it. 

“Well I’m going to take a shower and I suggest you do the same.”

Sans shrugged and went to go to the guest bathroom.

~~~~~~~~~~~

“Okay, the whole killing thing was great! You did exactly what you needed to do.”

“But…” Nightmare said ready to get a lecture.

“But you need to be scarier, the way you talk for instance.”

“What's wrong with the way I talk?”

“Well you sound so scared and nervous, your voice has to be fierce and strong! You are definitely not there yet.”

“Alright…”

Sans brought on a piece of paper with Dream's face on it and covered his face, Nightmare was not comfortable with this at all.

‘Okay try to talk to me in the worst way imaginable.” Nightmare looked at Sans and tried not to laugh at how dumb he looked, he tried to make a stern face before speaking.

“Dream… Fuck off.” 

“Uhhh no man, you just sound annoyed, not mad or scary.”

“But..”

“Cuss words are not scary,” Sans got up to Nightmares face and had a sly smile.

“But I can fucking make it scary~” Nightmare felt himself sweat before he pushed Sans away nervously.

“See? You got scared and I didn’t even do anything, that’s what you should be doing.”

“I don’t know if I can…” Sans was getting frustrated and tried to think of an idea.

He brought out a dummy he found in a spare room and pointed to it, he taped Dream's face to it and held Nightmare's shoulder.

“What did Dream ever do for you? Hit you, made rumors against you, turned the multiverse against you?” What's next, you can’t even go anywhere without people screaming and attacking you.”

Nightmare felt the strong emotions of negativity and his face went hard, he walked up to the dummy Dream and began speaking.

“You never tried to defend me.. All you did was get the respect of everyone else and you shoved me away, well now it’s time for some payback huh? Can’t wait to see your face once I destroy everyone you love, because I know I’m not one of them anymore uh Dream?” A tentacle choked the neck of the dummy and Nightmare gave a sick smile.

“This is what you get for all the shit you put me through, the rumors, the lies, the pain… ALL OF IT!” The neck broke off and the head hit the ceiling and fell to the floor, Nightmare took a deep breath and turned to Sans who gave a thumbs up.

“I have never been so proud..”

**Notes for the Chapter:**

> I tried writing the news in bold but it won't work here so that made me sad, hope it's not confusing reading it :(  
> Sans is doing a great job of training Nightmare, even though he doesn't like the approach.
> 
> Thank you for reading!


	5. The Boss

**Notes for the Chapter:**

> Nightmare is not the same person, at least not fully.

“Ready?”

“Ready!”

It had been a month since Nightmare took Sans in and since Sans taught Nightmare to be strong. Sans had started calling him ‘Boss’ to make him seem strong and professional, Nightmare loved the name and relished the praise from Sans every time he stroked fear into people. 

“Hey Boss I’ve been meaning to ask you, would you mind calling me Killer?”

“Killer? Why Killer?”

“Well I’ve been hearing people talk about me and they all say the same thing, I’m a killer and that’s all I’ll ever be.” Nightmare felt bad and put a hand on Sans’s shoulder.

“You don’t deserve to be called that Sans I’m sorry.”

“What are you talking about? I love that name! Killer is a great name and I can surely live up to it.”

“Oh! Uh okay, if you're fine with that I’ll call you Killer from now on.”

They were on a mission as Killer liked to call it where they would cause trouble, it was good bonding for them and good exercise for Killer. They went to an undertale AU and they went to go steal some things and break everything they saw. 

“Nightmare what are you doing??” Dream screamed from the rooftop he teleported on, he was able to see how much damage he and Killer caused. Nightmare smirked, ready to finally blow out on Dream for the shit he’s been through. 

“Dream what a pleasant surprise, like what I’ve done with the place?” He used a tentacle to strike a blow into the building Dream was standing on which toppled down, Dream fumbled and teleported down. He stood up and raised his bow at Nightmare's head, Dream tried not to say anything but for the first time, he felt genuinely terrified of Nightmare. 

“What's wrong, Dream? Got something to say~?” A tentacle suddenly threw itself to Dream and threw him into the remains of the building, he yelped at the impact and struggled to get up. 

“Go get him Boss!” Killer cheered as Nightmare walked closer to the golden skeleton.  
“Why are you doing this?” Dream pleaded only to get a dirty look from his brother. “Why?”

“Why did you always attack me when I never did anything? Why was I always being beaten and shot by you? Why did you smile every time like you enjoyed hurting me? You say I’m your brother but you punish me for fucking breathing…”

He said nothing and felt tears pour down his eyes, Nightmare read genuine remorse from Dream but the damage was done and he was in pain because of him. A tentacle curled around his waist and Dream was thrown into another wooden building that broke down. Nightmare was instantly slapped with a brush by Ink in retaliation, Killer ran behind Ink and sliced his side.

“Come on rainbow, let’s dance~” Inks eyes turned red in anger as he stepped forward, his brush was swung at Killer who was thrown back. Killer was grinning like a maniac every time Ink got close and it made him smile even more when Ink would flinch. 

“What’s wrong Inky? Ya scared??”

“Shut up.” Ink swung once again at Killer in close range but didn’t expect for him to dodge and get a knife at his neck.

“What did you say to me?” Nightmare walked to the two and tapped Killer on the shoulder, he motioned for him to let Ink go and he did.

“I've had enough fun for today, let's go home.”

“You got it Boss!” They leave Dream and Ink with scared monsters and a destroyed town.

“Hahaha, that was great! Boss, I am so proud of your progress.”

“Thanks, Killer, I appreciate it.”

Killer passed a root beer to Nightmare who happily grabbed it and took a sip.

“You're glad that you decided to stay there huh?”

“Yeah, too bad I still have a scar from Grillby though.” Killer commented as he peered down to his leg, the leg had grey lines on the bone which showed where it was cracked.

“But hey I have a good story to tell with this bad boy.” He boasted as he smacked his scar, Nightmare chuckled and turned on the TV.

“Breaking news, Dream and Ink have been attacked and assaulted by Nightmare and his supposed partner in crime. Right now they are getting the best care in the multiverse but they have destroyed an Undertale AU, leaving many monsters scared and dead. Today the world feels a little more negative as Nightmare has won today's battle.” 

“YEEAAAAHHHH!!.” Killer smashed his bottle to the floor and started to shake Nightmare back and forth.

“We did it! They’re finally taking you seriously!” Killer happily exclaimed as Nightmare laughed and patted his shoulder.

“Woah so this how it feels? I feel great!” Nightmare said as he sat down in relief, no one would mess with him like this now. Killer had never been so happy to be alive than now.

“So Boss what are you planning to do now?”

“Keep doing what we're doing right now, attack, and have a good time.” Nightmare stopped to ponder something before throwing an idea at Killer. “How do you feel about letting another person join us if the time is right? For instance, we find another person who may be in need of help..?”

“Boss you’re too soft, but because you’re in charge I wouldn’t oppose the idea. I still get to mess with them though!”

“Killer, I already knew you were going to do that, I didn’t even need to hear it.” Nightmare jokingly said as he grabbed a dustpan and broom. He went to clean the glass shard while hoisting Killer up in the air so he wouldn’t step on the shards, he told Killer he was too messy.

“Haha, do you even know how to clean Boss?”

“Yes, I know a lot of things- Hey are you okay?” Killers black tears were oozing out, even more, he started to cough and black came out of his mouth. Nightmare put him on the couch and crouched down not knowing what to do, he didn’t make a move as the black dripped from his hands to the floor.

“Killer… Killer? Can you hear me??” He pleaded to Killer who only coughed violently in response, grabbing his soul he was taken back to see a circle instead of a heart. The soul was pulsating and shook rapidly under his hold, he had no idea of what to make with this. For now, he went to grab a bucket for the poor monster, he sat next to him and rubbed his back comfortingly. Killer started to vomit into the bucket as more tears ran down his sockets, Nightmare could tell he was actually crying this time but said nothing. 

After an hour of vomiting and crying, Killer was able to finally form a sentence. “Thank you..”  
Nightmare sighed in relief and had Killer lean on him for support. He was exhausted and just wanted to nap already, he found himself pretty comfortable next to Nightmare like this. 

“Go to sleep Killer, I'm here for you.” 

“...I didn’t cry.”

“I know you didn’t.” Nightmare lied as Killer finally closed his eyes, he found himself sleepy from worrying too much and fell asleep quickly. 

~~~~~~~~~

“I got that from the human once I killed them, I don’t know how long that will happen for or if it’ll happen again..”

“It’s fine Killer, we’ll be prepared next time for it but don’t overstress okay?” Killer nodded and wiped a bit of black from his chin once again. Nightmare was quick to grab a snack for him, he never wanted to see Killer do that again. 

“Killer do you need anything?” 

“Nah it’s okay I got the chips.”

“That's not gonna be enough for you,” Nightmare said as Killer waved him off. He wasn’t a damsel in distress and he definitely didn’t need to get babied around. Nightmare was definitely a mother goose.

“Boss stop dotting on me, I’m fine… maybe a bit tired but I’m fine.” Nightmare instantly grabbed Killer's bridal style and headed off to Killer's room. Killer rolled his eyes and waited to be put to bed for a well-deserved nap. 

“Are you sure you don’t need anything?” Nightmare asked once again as he tucked Killer in.

“No mom I’m okay thanks though,” He replied snuggling in his blanket and quickly falling asleep. Nightmare chuckled to himself and closed the door behind him. He really wanted to do something nice for Killer, he’d done so much for him…

Killer woke up three hours later with the worst headache, he sat up from the bed and looked around. He was almost surprised Nightmare wasn’t there since he kept coddling him. He steadily got up and went to the living room when the smell of potatoes filled the air. Wandering through the kitchen he saw Nightmare mashing them together with a spoon, he turned to Killer and smiled.

“Hey, Killer how are you feeling?”

“Better now, thanks,” Killer answered before he got closer. He looked to a pan and was surprised to see the food wasn’t burnt, the food smelled amazing. 

“Wow Boss, I am surprised you made something like this."

“You’re in for a real treat then, look in the oven.” Killer shifted his gaze to the oven where he saw cookies baking inside. 

“Dang, you’re making a full course meal today huh?”

“Only for the best,” Nightmare answered as he put the mashed potatoes on two plates. He went to the pan and took out two seared steaks as well. He carried Killer to the table and made him sit down as he put a plate in front of him. Killer thanked Nightmare for dinner and began to eat, it was so good! He was lucky Nightmare could actually cook as eggs were the only thing he knew how to make. He was smiling the whole time and decided to make some jokes at Nightmare who laughed the whole time. He didn’t feel lonely anymore with Killer around and he hoped he would never leave his side.

**Notes for the Chapter:**

> Killer just wants people to know what he does, he's not scared of anything. Nightmare just is happy that he has someone around, even if he is an absolute maniac. 
> 
> Thank you for reading! Next on the list is Cross, get ready for the soft boy!

**Author's Note:**

> Sans is gonna be in for a rude awakening if he can even get up that is...
> 
> Thank you for reading!!


End file.
